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Table 2 Distribution of key covariates among 157 boys and 176 girls

From: Fluoride exposure and pubertal development in children living in Mexico City

Variables   Min 10% 25% 50% 75% 90% Max p-valuea
Child’s age (years) Boys 10.7 11.5 12.2 13.4 15.8 17.2 17.7 0.70
Girls 10.8 11.4 12.0 13.5 15.8 16.8 17.8  
BMI-for-age z-score Boys −3.8 −1.6 −0.6 0.5 1.6 2.3 3.5 0.22
Girls −2.9 −0.9 −0.3 0.5 1.5 2.2 3.3  
Maternal education (years) Boys 6.0 9.0 9.0 12.0 12.0 16.0 20.0 0.43
Girls 2.0 7.0 9.0 11.0 12.0 16.0 21.0  
Number of siblings at birth Boys 1.0 1.0 1.0 2.0 3.0 3.0 6.0 0.49
Girls 0.0 1.0 1.0 2.0 3.0 3.0 5.0  
Urinary fluoride (mg/L)b Boys 0.15 0.38 0.48 0.63 0.77 0.97 3.01 0.64
Girls 0.05 0.34 0.43 0.57 0.75 1.09 2.61  
   Boys    Girls     0.39
Marital status   N %   N %    
Married   119 75.8%   126 71.6%    
Not married   38 24.2%   50 28.4%    
  1. aAnalysis of differences in key covariates by child sex bSpecific gravity-adjusted childhood urinary fluoride